"Or Fokkers," added the flight-sub. "Two of the brutes; they'll be hard after us in a brace of shakes. In fact I think they are heading in our direction already."
"Thank heaven it's getting dark," said the sub. fervently, for already the land was shrouded in the gloom of twilight. "And it's getting fairly thick up here. I can hardly discern the aeroplanes."
"They have a bigger object to look for than we have," said Fuller. "We'll have to do one thing or the other—go up or down. Going down means irreparable loss of hydrogen."
"There's nothing left in the way of ballast to sling overboard."
"Yes, in due course," remarked the flight sub. "I see a couple of straps round the basket. We'll have to strap ourselves to the netting and cut the car adrift. It's our only chance."
Tressidar realised the gravity of the situation. The balloon, by no means fully inflated when they boarded her, was appreciably losing lifting power both by the minute yet none the less certain porosity of the envelope and by the fall of temperature. He shuddered, strong-minded though he was, at the idea of having to literally hang in the air with the prospect of a terrific drop to earth should the thin cordage of the netting give way.
Presumably the German airmen were reluctant to plunge into the mist, that was now spreading far and wide and increasing in height. They were still climbing spirally, evidently with the idea of gaining an immense altitude before swooping down upon the derelict balloon.
And every moment's delay meant that their chances decreased and that the odds against the fugitives diminished.
The balloon, still falling, was now swallowed up in the fog. To descend prematurely meant either falling upon the German island of Rom, or else into the German territorial waters. In either case recapture was a foregone conclusion.
The low drone of an air propeller announced the disconcerting fact that one of the Fokkers was approaching. Quickly the noise increased, but in which direction—whether above or below—neither of the British officers could determine.